Lower Central & Lateral Incisor

Ist Dental Students - Morphology

2. Contents
■Morphology of Permanent Mandibular Central Incisor
■Chronology and dimensions of Mandibular Central
Incisor
■Brief morphology of Mandibular Lateral Incisor

Objectives
■Identification of mandibular incisors from other teeth
■Understand the morphology of mandibular central and
lateral incisor
■Distinguish between the labial, lingual, mesial, distal and
incisal surfaces of the mandibular incisors

3. Introduction

Mandibular incisors are four in number

Mandibular central incisor and lateral are similar in
anatomy and complement each other in function

They are smaller than the maxillary incisors

Mandibular central incisor erupts between the age of 6
and 7

Mandibular lateral incisor erupts between the age of 6
and 8

4. Mandibular Incisors
2
1
2
1
1 : Mandibular Central Incisor
2 : Mandibular Lateral Incisor

5. Mandibular Central Incisor
■Mandibular Central Incisor is the smallest tooth in
the dentition

6. Labial aspect

7. Labial aspect
■Labial surface of mandibular central incisor is very
small. It is the narrowest tooth mesiodistally of all
the permanent teeth



Narrowest tooth in the dentition

8. ■It is bilaterally symmetrical

■It is the only incisor where both mesioincisal and
distoincisal angles are sharp and at right angles



Labial aspect
Both mesioincisal and
distoincisal angles are sharp

9. Lingual aspect

10. Lingual aspect
■The lingual aspect is concave from the incisal edge to
the cervical line

■Cingulum is smooth and barely visible

Shallow lingual fossa and
smooth cingulum

11. ■The surface is smooth and devoid of any grooves. No
other tooth in the mouth, except the mandibular
lateral incisor, shows so few developmental lines and
grooves.

12. Mesial aspect

13. Mesial aspect
■The labial outline is almost straight, except near
cervical third where it is convex

■The labial surface is inclined lingually


Labial surface inclined
lingually

14. ■The lingual margin is ‘S’ shaped

■The cervical line on the mesial and distal surface is
convex incisally


S’ shaped lingual surface‘
Cervical line convex incisally

15. Distalaspect
●Distal surface is very similar to the mesial surface.
●The cervical line is less curved.

Distal aspect

16. Incisal aspect

17. Incisal aspect
●This aspect illustrates the bilateral symmetry of this
tooth.







●The labiolingual diameter is greater than mesiodistal
diameter.




Bilaterally symmetrical
Labiolingually bigger
than mesiodistally

18. ■Newly erupted teeth show mamelons which wear off
upon mastication



Mamelons

19. Root
▪The root is single and straight.

▪ The deflection of the root if present is on the labial or
distal side.
Single and straight root

20. 3.0 2.0

5.3

6.0

3.5

5.0

12.5

9.0
Curvature of
Cervical Line
M D
Labiolingual
Diameter at
Cervical Line
Labiolingual
Diameter at
Crest of Curvature
Mesiodistal
Diameter at
Cervical Line
Mesiodistal
Diameter at
Contact Area
Root
Length
Crown
Length
Average Dimensions in millimeters
CHRONOLOGY
Appearance of enamel organ5 m.i.u
First evidence of calcification3-4 months
Crown completion4-5 years
Eruption6-8 years
Root completion10 years
Contact Area
Man L.I

Mesial Distal
I
3
I
3

I
3
- Incisal third

21. Mandibular Lateral Incisor
■Mandibular lateral incisor is slightly wider
mesiodistally

22. ■The cervical portion of the lingual aspect is narrower
while the incisal portion is wider. This gives the crown
a more or less a fan shaped appearance


Cervical portion narrower
Fan shaped appearance

23. ■The concavity in the lingual aspect is slightly more
when compared to mandibular central incisor

■The incisal edge follows the mandibular arch, giving
the crown a slightly twisted appearance on its root

Lingual fossa more concave

24. Labial aspect Lingual aspect
Mesial aspect
Distal aspect
Incisal aspect